I’d hate to learn English as a second language simply because of weird stuff like ‘hotbed’ being one word and ‘hot tub’ being two words. Where’s the logic in that?
an area having rails or rolls on which rolled pieces are laid to cool.
hot·bed, n., v., -bed·ded, -bed·ding.
1. a bottomless, boxlike, usually glass-covered structure and the bed of earth it covers, heated typically by fermenting manure or electrical cables, for growing plants out of season.
2. a place or environment favoring rapid growth or spread, esp. of something disliked or unwanted: a hotbed of disease.
3. Slang. a bed shared by two or more persons in shifts, each sleeping in it for or at a designated time and then vacating it for the next occupant.
4. Slang. to share a bed in shifts, so that it is always occupied.
[1620–30; HOT + BED]
Hot tub: a wooden tub, usually large enough to accommodate several persons, that is filled with hot aerated water and often equipped with a thermostat and whirlpool: used for recreation or physical therapy and often placed out of doors, as on a porch.
People may place plants in a hotbed, whereas people plant themselves in a hot tub. How confusing is that to someone learning English.
A hot tub can also be a hotbed of disease if not properly maintained.
I made the words ‘hotbed’ and ‘hot tub’ while working on my next word puzzle ebook. It is a 6-letter word ebook and I was making as many 6-letter words as I could from the phrase “ODD ABOUT THE”. (I found 16 six-letter words. Try it yourself and see how many you find using each letter only once.)